Generally, an electron beam apparatus of a ring type is represented by an electron synchrotron, an electron storage ring or an electron collider. In such an electron beam apparatus, there is an effect that by synchrotron radiation (abbreviated to SR), thermal motion within a plane normal to the direction of the beam is increased simultaneously with occurrence of reduction and unification of energy in the traveling direction of the beam. When the increase of thermal motion within the normal plane is more strictly defined in terms of another expression, this mans that an emittance increases which is defined as a product of an inclination angle of an electron beam with respect to an axial direction by an extension of the electron beam within a plane normal to the axial direction. With the increase of an emittance, a deviation amplitude of an electron beam in the ring from a reference orbit would become large and eventually electrons dropping out from a stable orbit would be produced. Such electrons bombard an inner wall surface of a vacuum chamber forming the ring and kick out an adsorbed gas and a part of the inner wall constituent material from the inner wall, and these would enter into the electron beam, resulting in deterioration of the beam. A basic cause of the limit of the beam storage time within the electron beam storage ring resides in deterioration of beam quality caused by increase of an emittance of the electron beam accompanying the SR.
Therefore, if an emittance of such an electron beam is reduced to an extremely small value, improvement in a storage time of an electron beam in a storage ring and high luminescence version of an SR or high qualification of a beam issued from an electron accelerator can be realized.
On the other hand, in an apparatus of charged particles other than electrons, that is, an ion beam, while SR is not generated, an emittance of an ion beam derived from an ion source is usually large as compared to the case of electrons, and consequently, requirement for improvements in an emittance is intense similarly to an electron beam apparatus.
Among charged particle beams, in order to realize high quality version of an electron beam, it is required to make an emittance of an electron beam extremely small simultaneously with realization of uniform distribution of energy by cooling an electron beam, but a method for improving an emittance has not been invented so far.
On the other hand, for the purpose of unification of beam energy of charged particles other than electrons, that is, ions and improvement of an emittance, a method relying upon compensative acceleration control called "stochastic cooling method" has been put in practical use. However, this method necessitates a long time for cooling of an ion beam, and is therefore available neither for a rapid-cycling accelerator nor for a charged particle storage ring equipped with an internal target. For instance, in order to unify energy of a proton beam up to one in thousands, several minutes are necessary, and it is difficult to put this method in practical use.
An object of the present invention is to provide a charged particle beam cooling method, which resolves all these problems and which momentarily cools every charged particle beam regardless of a pulsed beam or a continuous beam.